London - Great Britain's world cycling road race champion Lizzie Armitstead said on Wednesday "incredibly difficult" family circumstances caused her to miss a pre-Olympics drugs test.
UK Anti-Doping (UKAD) provisionally suspended Armitstead on July 11 for failing to correctly notify testers of her whereabouts, which led to her missing three drugs tests within a 12-month period.
But the Court of Arbitration for Sport (CAS) said procedures were not followed correctly for one of the tests and upheld her appeal, clearing the 27-year-old to race at the Olympics.
Armitstead missed the third test, on June 9 this year, due to a serious family illness and said in a statement posted on Twitter: "My personal family circumstances at the time of the test were incredibly difficult.
"In my defence, I was dealing with a traumatic time and I forgot to change a box on a form. I am not a robot, I am a member of a family - my commitment to them comes over and above my commitment to cycling."
She added: "I love sport and the values it represents. It hurts me to consider anybody questioning my performances.
"I am sorry for causing anyone to lose faith in sport. I am an example of what hard work and dedication can achieve. I hate dopers and what they have done to sport."
Armitstead is one of the favourites to win gold in the women's road race in Rio on Sunday. She won silver in the event in London four years ago.
Armitstead was charged with three "whereabouts failures" last month, leading to a suspension pending disciplinary action.
The first missed test was at a World Cup event in Sweden in August 2015, the second was in October 2015 and the third was in June this year.
Armitstead admitted fault with the second two missed tests, but successfully appealed to CAS over the first, which happened at a GB team hotel.
CAS ruled that the UKAD doping control officer had not made reasonable attempts to locate Armitstead at the hotel.
In an interview with the Daily Mail, Armitstead admitted she had been "very naive" not to contest the first missed test.
British track and field athlete Christine Ohuruogu, the 2008 Olympic 400m champion, was banned for a year by UKAD following three missed tests in 2006.